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Microbiology Part 1 > Lec11 Neisseria and gram negatives > Flashcards

Lec11 Neisseria and gram negatives Flashcards

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1
Q

What types of bacteria does spleen play essential defense role?

A

encapsulated organisms

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2
Q

How can polysacccharide vaccines be altered to create longer lasting immunity? Why?

A
  • by conjugating them to proteins

- this helps because proteins are more immunogenic than protein

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3
Q

What are the visual differences between meningococcus and pneumococcus both of which can cause meningitis?

A

pneumococcus: gram pos, diplococci
meningococcus: gram neg, kidney bean shaped cocci

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4
Q

Who gets meningitis?

A
  • peak incidence age 6 mo to 2 years
  • conditions of overcrowding
  • those with splenectomy
  • those with late complement deficiencies
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5
Q

Where does neisseria meningitis colonize? how is it transmitted?

A
  • colonized nasopharynx in healthy people
  • causes life-threatening infection when reaches bloodstream or CNS
  • transmitted by respiratory droplets
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6
Q

What are the virulence factors of N. meningitis?

A
  • secretes IgA protease
  • —- allows survival in respiratory tract
  • pili
  • —- mediate attchement to respiratory epithelium
  • Opa and Opc proteins
  • —- allow to be engulfed by respiratory cells
  • capsule
  • — antiphagocytic
  • lipooligosaccharide
  • — endotoxin that triggers sepsis
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7
Q

What is rash like in mengingococcemia?

A
  • cap appear as petechiae, purpura, or hemorrhagic bullae

- always non-blanching

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8
Q

WHat happens when LPS endotoxin released?

A
  • released when bacterial cell dies

- riggers fatal downstream events

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9
Q

How many serogroups in N mengingitidis? which are most important?

A
  • 13 serogroups
  • determined by polysaccharide capsule
  • most important A, B, C, W-135
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10
Q

Which serogroups are in the polyvalent vaccine?

A

A, C, Y, W-135

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11
Q

Why are vaccines against group B mengingococcus complicated?

A
  • B has a polysacchardie capsule similar in struct to human sialic acid
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12
Q

besides meningitis, what other infections is neisseria meningitidis associated with?

A
  • meningococcemia
  • respiratory tract infection
  • pneumonia
  • otitis media
  • conjuncitivitis
  • septic arthritis
  • pericarditis
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13
Q

What is treatment for n. meningitidis?

A
  • cephalosporins [ceftriaxone] most common

- pencillin [one of few gram neg that does not produce beta lactamase]

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14
Q

What is empiric treatment of bacterial meningitis [when no organism on gram stain]?

A
  • ceftriaxone [against meningococcus, haemophilus, and pneumococcus]
  • vancomycin [because of beta-lactam resistant pneumococcal strains]
  • sometimes steroids [to minimize inflammatory response]
  • sometimes ampicillin [against listeria]
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15
Q

What is shape of listeria monocytogenes?

A
  • gram positive rod

- tumbling end of end motility

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16
Q

Who is most susceptible to listeria?

A
  • infants and elderly [bimodal distribution]
  • immunocompromised
  • pregnant women
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17
Q

What drugs do and do not have activity against l. monocytogenes?

A
  • cephalosporins do not have reliable activity

- ampicillin does have activity

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18
Q

When is mengitis chemoprophylaxis used?

A
  • for close contacts of index case

- can prevent invasive disease if given within 14 days of exposure

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19
Q

How do you differentiate N. gonorrheoeae and N. meningitidis?

A
  • N gonorrhoeae does not have true polysaccharide capsule
  • N. gonorrhoeae only utilizes glucose
  • N. meningitidis utilizes glucose or maltose
20
Q

What are the virulence factors for N. gonorrhoeae?

A
  • similar to N. meningitidis

- pili assist binding human mucosal surfaces

21
Q

Which patients are most at risk for N. gonorrhoeae?

A
  • 15-25 year old men and women highest rate

- high risk in patients with terminal complement deficiencies

22
Q

What are symptoms of gonorrhea?

A

about 10% asymptomatic

  • infection of genitals
  • foul smelling purulent discharge
  • inflammation, redness, dysuria
23
Q

What are the diseases associated with N. gonorrhoeae?

A
  • ophtalmia neonatorum: transmitted from mother to child in delivery
  • pelvic inflammatory disease
  • pharyngitis
  • perihepatitis [fitz-hugh-curtis syndrome]
24
Q

What are symptoms of pelvic inflmmatory disease?

A
  • chronic infection causes damage to fallopian tubes, sterility, ectopic pregnancy
25
Q

What is used to diagnose gonorrhea [GC] and chlamydia?

A
  • low sensitivity to culture

- use DNA probes

26
Q

What is the treatment for N. gonorrhoeae?

A
  • not penicillin [it has beta lactamase]
  • increasing resistance to fluoroquinolones is major problem
  • treat mostly with cephalosporins
  • co-infection with chlamydia assumed
27
Q

Where do we get L. monocytogenes?

A

from unpasturized cheeses

28
Q

Where can you grow haemophilus?

A
  • doesnt grow well on normal blood agar
  • grows on chocolate agar that contains lyes RBCs
  • grow on normal agar with factors V and X
  • use satellite colonies
29
Q

What is the satellite colonies technique for visualizing haemophilus?

A
  • put on single streak of staph aureus
  • make lawn of sample all around rest of plate
  • staph aureus will cause hemolysis of RBCs and haemophilus can grow in this hemolytic zone
30
Q

What is factor V?

A
  • nicotinamide adenine dinucleotide [NAD]
  • normally secreted by staph aureus
  • needed for haemophilus growth in culture
31
Q

what is factor X?

A
  • hemin

- intracellular heme released by hemolysis of S. aureus

32
Q

What diseases does H influenzae cause?

A
  • meningitis
  • otisis media
  • sinusitis
  • epiglotitis
  • tracheobronchitis
  • pneumonia
  • bacteremia
33
Q

What is the Hib conjugate vaccine made of?

A
  • capsular polysacchardies contjugated to proteins
34
Q

What disease associated wtih haemophilus ducreyii?

A
  • STD chancroid: painful ulcer in association with enlarged tender lymph nodes
35
Q

How does haemophilus ducreyii appear on slide?

A

school fish conformation

36
Q

What are micro properties of moraxella catarrhalis [shape, gram, etc]?

A
  • small gram negative
  • diplococci
  • catalase positive
  • aerobic
37
Q

What diseases does moraxella catarrhalis cause?

A
  • otitis, sinusitis, pneumonia [especially in patients with emphysema]

usually upper respiratory infection

38
Q

What are micro properties of bordetella pertussis? [shape, etc]?

A
  • small gram negative

- coccobacillus

39
Q

What does bordetella pertussis cause?

A
  • whooping cough
40
Q

What is DPT vaccine?

A

vaccine for diphtheria, pertussis, tetanus

41
Q

What is virulence factor of bordetella pertussis?

A

A-B toxin

42
Q

What is treatment for bordetella pertussis?

A
  • usually just supportive

- in some situations use azithromycin

43
Q

What are the 3 phases of whooping cough?

A

catarrhal: non-specific flu-like symptoms – non productive cough lasts 2 weeks, highly contagious
paroxysmal: repetitive coughing with whooping sound, vomitting, cyanosis
convalescent: paroxysmal cough gets slightly better, development of pneumonia, seizures, encephalopathy

44
Q

What are the 3 encapsulated organisms that pts without spleen need to be vaccinated for?

A
  • strep pneumoniae
  • neisseria meningitidis
  • haemophilus influenzae
45
Q

What is the major cause of bacterial meningitis?

A

n. meningitidis

46
Q

What is shape/micro features of neisseria meningitidis?

A
  • gram negative

- diplococci

Microbiology Part 1 (24 decks)

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